Euskal Oiloa Chicken Forum

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Re: sex linked traits

Ipf in reference to your comment "All loci on the same chromosome are linked to each other, by definition", this is reason I posed the question:

A distance of 50 LMU corresponds to independence. Note that, if two gene loci are far enough apart on a large chromosome, the crossover rate between them may be so high that they will map as if they are not linked.http://www.cod.edu/people/faculty/fanch … emapping2.

I am not sure how large the Z chromosome is but I wondered if perhaps some of the traits were located far enough apart that they do not appear linked.

Re: sex linked traits

ABSTRACT1. The ladykiller (lk) gene has been located on the sex chromosome of the fowl. It is 4.2 map units distant from the feathering rate locus (k) and 11.2 map units distant from the dwarf (dw) locus.

2. Most of the embryonic mortalities associated with this gene occurred between 3 and 4 d of incubation.

Re: sex linked traits

PG - yes of course, you are correct, if they are far enough apart they don't appear to be linked. I guess it depends on how you define linked - is it "tend to be inherited together" or "located on the same chromosome"? Functionally the first of course makes more sense, but as an admitted theorist, I tend to think in terms of the second.

The Z chromosome is pretty big - the 5th largest. For comparison, chromosome 1 has 195,000 bases(195 Mb), and chromosome 3 has 110 Mb. The Z contains about 82 Mb and about 1000 genes. It is less gene-dense than any chicken autosome, with 11 genes per megabase, which is less than half of the chicken autosomal average of 25 genes per megabase.